Automatic vial-forming machines forming vials from borosilicate glass tubes include a vertical type and a horizontal type. In both cases, vials are produced by first forming a mouth of a vial and then forming a bottom of the vial. Chemical quality of the resultant vials are evaluated by a value of eluted alkali measured by Method 2 (internal surface method) defined in the Japanese Pharmacopoeia or a testing method in conformity with the same. To obtain vials with low alkali elution, it is general practice to perform a process operated at low temperatures for a long time, away from use of a process operated at high temperatures for a short time.
However, even if the vials are produced by the low-temperature process, they have a deteriorated region caused by processing in the form of a belt on the internal surface close to the bottom of the vial, which has problems such as, for example, alkali elution affecting pharmaceutical products contained therein. This deterioration caused by processing is considered to be a phenomenon such that alkali-containing materials exuded from or vaporized from the glass are condensed to a plurality of small droplets and deposited on the internal surface of the vial in the process of forming the vial bottom from the borosilicate glass tube.
In order to lower or prevent elution of alkali from the condensed droplets on the internal surface of the vial, some processes have been proposed that include a method (S method) of allowing the alkali in the deteriorated region to react with sulphate ions at the final stage of vial forming process, and then washing the vial with water to remove alkali as sodium sulphate (Na2SO4); and a method of covering the internal surface of the vial with a thin film of silica (SiO2) by chemical vapor deposition (CVD) to prevent elution of alkali. However, the S method requires an increased cost form washing the vial to remove white sodium sulphate produced on the internal surface of the vial and the internal surface after alkali extraction has a markedly uneven cratered surface. On the other hand, the method of covering the internal surface of the vial with the silica thin film results in increased processing cost.    Patent document 1: JP H06-45481B    Patent document 2: JP H06-76233B    Patent document 3: JP 3,268,470